Associated with a trend toward miniaturization and high performance of an electronic device in recent years, in a multilayer printed wiring board, high wiring density and high integration have been developed. Following this, a demand for reliability enhancement due to enhancement in heat resistance of a laminated plate for multilayer printing wiring is being strengthened. In such an application, particularly in a semiconductor package, the laminated plate is required to have both excellent heat resistance and low thermal expansion properties. In addition, dielectric properties responding to high frequency of electric signals are also required.
In this issue, though known liquid crystalline polymers such as polyesters, polyamides, polycarbonates, polythiols, polyethers, polyazomethines, etc. are a thermosetting resin having excellent low thermal expansion properties, dielectric properties, and heat resistance, they involved a problem in workability or moldability and also a problem of difficulty in handling because of low solubility in an organic solvent.
Among these liquid crystalline polymers, since G.F.D'Alelio discovered a polyazomethine that is a liquid crystalline oligomer (see NPL 1), a large number of examples regarding resins using a polyazomethine have been reported (see PTLs 1 to 7).
PTL 1 discloses a variety of polyazomethines, and PTLs 2 to 7 disclose polyazomethines having a specific structure. In addition, PTLs. 8 and 9 disclose thermosetting polyazomethine resins containing an unsaturated group and describe that high heat resistance is revealed by these resins.